Various types of image forming apparatuses are well known which form an image on sheet media based on the image data. For example, listed are a printer which forms the image data, transmitted from a computer, on the sheet media, and a copy machine which reads the image from a surface of a document and copies it. Further, listed are compound machines, in which a printer and a copy machine are combined, or a compound machine, in which a facsimile machine and a scanner are further added to the former.
Various types of sheet media are accommodated in a sheet storing device which is installed in or pre-positioned to said image forming apparatus, and any type of sheet media is picked up for image formation. Listed sheet media are, for example, light weight coated paper for hand bills, art paper for trade catalogs, coating paper, cast paper, and bond paper, as well as paper having punched holes on its one side for use in loose-leaf binders.
The operator may select one type from among the stored sheet medias, select either a single-surface printing operation or double-surface printing operation, and may further select a binding direction, after which the operator allows the image forming apparatus to form the image in the desired format. Unexamined Japanese Patent Application Publication No. 7-131,630 discloses the binding direction for binding of a number of printed sheets, whereby binding can be selected among top binding, bottom binding, left binding, right binding, long edge binding or short edge binding. For the double-surface printing operation, the image on text to be printed on the second surface is rotated based on the selected binding. Further this technology discloses that the images are rotated based on the direction of the document to be read, or the direction of the sheet media.
For example, when sheet media is conveyed parallel to its long edge, for right or left side binding, the image to be printed on the second surface does not need to be rotated, however, for the top binding, only after the image to be printed on the second surface is rotated 180°, image formation is conducted. That is, the top of the image is aligned with the bottom of the second surface, for image formation.
However, if a sheet media carrying punched holes is selected as sheet media for the image formation, the position of the punched holes may not match the selected binding direction.
That is, in the case of an LEF (being long edge feed) transfer sheet, a sheet carrying punched holes on one of long edges, is selected, the binding direction may be any one of the left or right binding direction (being right side binding for LEF transfer sheet). However, if an experienced operator selects top binding (being the left side binding for an LED transfer sheet, the image on the second surface is rotated 180°, whereby if the sheets are bound using the punched holes, the image printed on the second surface becomes reversed for a person reading it, which becomes a major problem.